Considerable attention has been directed toward automated handling of mail. The automated handling of mail is a complex problem with many parts. No one singulation method alone appears to be a solution for all conditions. Instead, it appears that automated mail handling will require a combination of many different techniques. Thus, simplicity, cost and robustness become important considerations. Another aspect of the problem lies in identification of the shape and location of mailpieces which may have been dumped for sorting. This problem is exacerbated by the varied nature of mailpieces, ranging from single sheets of paper to magazines which are bound along one edge, letters of various sizes, and packages. Robots must be available which are capable of separating one piece of mail from another, picking up mailpieces as may be required without damage, and transporting them to appropriate locations such as bins.
One of the identification problems arises when boxes of envelopes are dumped onto a conveyor belt, and "fanned" in the direction of motion of the conveyor so as to generally separate the leading edges of one envelope from the other, leaving them substantially overlapped. A simple and robust arrangement for identifying the leading edge of a mailpiece is desired, using ordinary diffuse illumination such as is found in ordinary work places, without recourse to scanning, lasers, and the like.